U-238
The number besides the U means its total molar mass. The molar mass of this element is 238
Molar mass= protons + neutrons
This means that 238= 146 + protons
Do 238 - 146
Answer is 92
Answer: O fluorine to complete the octet rule
that right
Polylactic acid is the correct answer
Oxygen- atomic number 8
1s² 2s² 2px² 2py¹ 2pz¹